Biology of Picroside I and Picroside II Biosynthesis in a Medicinal Herb Picrorhiza Kurroa Royle Ex Benth

Abstract

Picrorhiza kurroa Royle ex Benth (Family: Scrophulariaceae) is a medicinal herb, mainly newlinefound in the North Western Himalayas. Extensive harvesting for pharmaceutical purposes, newlinelack of organized cultivation and unorganized methods of uprooting has put this herb in the newlinecategory of endangered species. The medicinal property of this plant is attributed to newlineconcentrations of picrosides, Picroside-I (P-I) and Picroside-II (P-II). Knowledge on factors newlineinfluencing the contents of P-I and P-II is lacking. We studied the presence of picrosides in newlinedifferent tissues, viz. shoot, root and rhizome, as well as in different growth and newlinedevelopmental stages coupled with the expression of MVA and MEP pathway genes. The newlineobjectives of stuy were outlined as under: newline Detection and quantification of P-I and P-II in different tissues and newlinegrowth/developmental stages of P. kurroa newline Expression analysis of MVA and MEP pathway genes vis-à-vis P-I and P-II newlinecontents in different growth stages of P. kurroa newlineP-I content increased from 0.05 % to 0.76 % in different growth stages of shoots. newlineSignificant increase in the contents of P-I (0.15 0.50 %) and P-II (0.1 0.45 %) was newlineobserved in rhizomes of different developmental stages. Highest amounts of P-I (8.7 %) newlineand P-II (5.3 %) were detected in uppermost part of mature dried rhizomes compared to newlinebottom part with 2.9 % and 2.2 % of P-I and P-II, respectively. P. kurroa grown at high newlinealtitude (Sairopa, 4,500 a.s.l) showed 1.75-folds increase in P-I in leaves whereas newlineexponential increase in the P-I content was detected (0.05 1.7 %) in the leaves of different developmental stages (L1-L5) of P. kurroa grown at lower altitude (Jagatsukh, 1,900 m). newlineVariation in amounts of P-I and P-II in different growth and developmental stages of P. newlinekurroa implied the importance of appropriate selection of plant material (rhizomes and newlineroots). Estimation of P-I and P-II in different tissues of P. kurroa showed that shoots contain newlineonly P-I whereas P-II is present only in roots. newline